1. Field of the Invention
The present is invention concerns the field of microbiological pathology and is more particularly addressed to a novel microbiological culture method and attendant apparatus that utilizes patient whole blood.
2. Description of Related Art
From the textbook of microbiology, Biology of Microorganisms, by Madigan, Martinko, and Parker, we learn that, "The most important activity of the microbiologist in medicine is to isolate and identify the agents that cause infectious disease." This is called the pure culture method of current practice, which proceeds by culturing a patient specimen or blood, thereby isolating and identifying pathogens, and using the resulting inoculum to make a pure culture, which may then be tested for sensitivity to antibiotics or other medications.
While much has been learned from this classic method, it has great limitations. The complex interrelationship of all the different microbes in a patient, with all the helpful and harmful elements in that host, are not considered as part of a whole. In research it is useful to study parts, but to treat an individual patient effectively, we must consider the whole person, at the time of inquiry. We must recognize that a human being is a mixed culture, and that pure cultures do not give physicians the information necessary to treat patients. This is vital at a time, as we are now experiencing, when pathogens are becoming resistant to antibiotics as well as more virulent.
This problem has long been recognized in microbiology, but broth cultures and mixed cultures were deemed too complex and too hard to work with. Agar culture media are difficult to use, and blood clots are difficult to deal with, so anticoagulants are routinely employed. Further, since labs are far distant, preservatives and refrigeration are necessary. Thus, artificial conditions, desire for convenience, and reliance upon pure cultures have left us less able to respond effectively to the pestilence of our times.
The process described herein considers the whole person, uses whole blood and specimen-not inoculum-and proceeds directly to the cure, not stopping to identify or isolate pathogens. The process is a basic simplification of microbiology/pathology (micropathology). Devices described herein allow the process to be used conveniently and protect personnel from potentially hazardous patient's blood. Availability of a process that can actually determine if a patient needs an antibiotic, and which one, may change the way antibiotics and other medications are prescribed.
The Problem
People become ill with pathogens, microbes such as bacteria, viruses, protozoa, fungi, yeasts, etc. Curative substances, e.g., chemical agents and antibiotics, penicillin for example, are used to inhibit the growth of, or kill, pathogen(s). Known sensitivity of a given pathogen to a specific antibiotic(s) allows the patient to be treated with that antibiotic, or combination, with a high probability of cure. The physician's dilemma is, how to determine which antibiotic or medication will be effective. But even before considering which antibiotic, the physician must determine if any antibiotic is indicated. Viruses and allergies can mimic bacterial infections but are not helped by antibiotics, which may actually worsen the condition. In addition, the unnecessary prescribing of antibiotics is part of the cause of pathogens developing resistance.
Currently, a patient with typical symptoms is treated with the antibiotic that has been effective in the past. However, many pathogens have become resistant to antibiotics which previously were effective. Because current art does not give the physician a practical means in the office to determine if an antibiotic is indicated, or which one of the many old or new antibiotics would be effective, the physician usually makes an educated guess and simply picks one, hoping it will help. The patient becomes the test of effectiveness. More and more often today, a previously effective antibiotic is ineffective for patients. Alternatively, the physician can take blood or a specimen from the patient-urine, feces, throat swab, sputum, cerebrospinal fluid, or pus-and send it to the lab for culture and determination of sensitivity of any discovered pathogens to antibiotics. Or, the physician can send the patient to a lab collection center for collection of an appropriate specimen.
Currently, laboratories are highly automated. Automatic technology and expert personnel are very expensive, resulting in one central lab with many peripheral collection centers. Consequently, the actual lab is often far distant from the physician or patient, requiring considerable time for specimens to be transported. Consequently, blood and specimens are usually refrigerated until they are received and tests have begun. Usually, additives to blood such as anticoagulants, preservatives, etc. are used as well. The distance of the lab does not allow freshly drawn unadulterated whole blood and fresh specimens at body temperature, natural human conditions, to be used in culture and sensitivity testing.
Currently, in the lab the specimen, other than blood, is placed in a sterile culture medium, usually agar in a dish, to grow the pathogen(s) causing the disease. Suspicious colonies of pathogens are identified and reported to the physician who can then prescribe medications based on known past sensitivity of that type of microbe. The study may be taken further. Colonies may be isolated and inoculum transferred to a sterile agar dish and recultured, then this pure culture tested for sensitivity to specific antibiotics. Unfortunately, the steps necessary to get a pure culture require considerable extra time.
When blood is cultured, liquid growth media, or broth, is used to permit complete mixing of the blood and medium. But the liquid state imposes its own limitations. The blood is mixed throughout the medium and is not contained within a space where pathogen colonies are more readily identifiable. Also, with broth there is no firm surface, as provided by agar, to streak with the patient's specimen. Also, if the specimen is added to broth and blood, some microbes may grow, but pathogens that need air for growth may be inhibited, and thus cannot not be discovered unless special steps are taken to aerate the broth. Also, most commercially available liquid blood culture media contain anticoagulants to prevent blood from clotting and clumping. Consequently, even if whole blood without anticoagulant were delivered to the lab, the culture medium would alter the natural state, defeating the attempt to create a surrogate host without artificial additives. The process of the present invention is not disturbed by natural clotting.
Currently, pathogens that are grown from broth are identified, isolated, and transferred to receptacles where colonies of microbes may be manipulated under controlled conditions, including testing for antibiotic sensitivity. Many steps and much time, labor, and expertise are required. Therefore, this method is little used except for the most critically ill, usually hospitalized, patients.
Currently, the process of mixing a patient's whole unadulterated blood directly with culture medium, such as agar, and adding a specimen, for growth of pathogens and antibiotic sensitivity, is not used. There are a number of factors mitigating against direct addition of blood to culture medium. Agar is difficult to work with; it either hardens or liquefies because of temperature changes. If heating is necessary, many pathogens in the blood are killed and cannot be discovered later. To make a pour plate to test sensitivity to antibiotics, inoculum is added to agar at 45+.degree. C., the lowest temperature agar is liquid. That temperature is unnatural to the human body, thus many pathogens that thrive at normal body temperature, 35-37.degree. C., are killed. Fragile anaerobic pathogens and some viruses, die upon contact with air. Other fragile microbes die when stained on a slide. Thus, current art is unable to readily culture and identify many fragile pathogens.
The handling of human blood is not without risk in this age of deadly pathogens such as hepatitis B, AIDS (HIV), and others. If the surface of agar were spread with a patient's specimen and the patient's blood were mixed with the agar using current means, e.g., a syringe/needle, personnel would be exposed to the risk of needle stick and the patient's pathogens. Devices are described herein that avoid or lessen that risk.
Currently, small paper discs which have been impregnated with different antibiotics, at various strengths, can be placed, one at a time by hand, upon the surface of agar where pathogens are growing. If the particular pathogen is sensitive to the antibiotic on the disc, a clear "zone of inhibition" will appear around the disc as the pathogen is killed or inhibited. This is not a practical method in the physician's office and, consequently, is little utilized at this time. In the lab, many discs can be placed on the surface of agar simultaneously by a special machine. But the lab is not where blood and specimens are fresh, and alive with microbes. Simple devices are described herein that simplify antibiotic testing in the physician's office where whole blood and specimens are fresh, allowing the culture of fragile organisms.
Disadvantages Of The Current Art
(a) Current microbiological art does not give the physician a practical means to determine if an antibiotic is indicated and, if so, which one. Consequently, patients are being given antibiotics that were effective, often in the hope of curing an infection that proves to be viral or at least of inhibiting a possible secondary bacterial infection. However, indiscriminate use of antibiotics and similar drugs is causing patients to become allergic to these drugs while the microbes become resistant. There are two dangerous consequences: the patient will not be cured of infection; and the patient becomes a host who may unknowingly be a carrier and transmit resistant pathogens. The process of using naturally augmented media to make a patient replica allows determination of the correct drug to use (i.e., antibiotic sensitivity) for individual patients because factors, both known and unknown in the patient's blood that will affect how a pathogen responds to a given antibiotic are automatically considered in this novel process of determining antibiotic sensitivity.
(b) A patient's unadulterated whole blood is difficult to work with since it coagulates and decomposes quickly. Consequently additives, e.g., anticoagulants and preservatives, and refrigeration are currently used, but this alters the natural state of the blood and limits what may be cultured from it. The process herein described, with accompanying devices, does not have this disadvantage.
(c) Specimens are routinely transported to laboratories for analysis but many pathogens are fragile and do not survive the trip. Samples are picked up from the physician's office and transported to the lab in sterile containers but not under natural conditions. Much time may elapse before the culture process is begun. Pathogens which are not vigorous enough to survive and replicate under these abnormal conditions cannot be identified.
(d) Many pathogens do not grow in culture media now in regular use. For example, sheep blood which has been heated to release iron is mixed with culture media, referred to as chocolate agar, to facilitate growth of certain pathogens. Sterility can be maintained. However, sterile killed sheep's blood does not replicate freshly drawn unadulterated whole human blood at body temperature, especially all the different elements in a specific patient's blood at the time the patient is experiencing a particular illness.
Also, liquid growth media, broth, normally has anticoagulant added, thereby altering the complex natural state of the blood. It is known that anticoagulant kills a certain percentage of some microbes in the broth. Thus, current broth methods may prevent blood culturing of fastidious organisms.
Other types of agar also use blood as one of their components. However, the blood is not the patient's blood, does not contain all natural elements, has been heated and is sterile, and thus cannot be a replica of that specific patient at that specific time of illness. Standard pour plate method adds inoculum to 45+.degree. C. agar, thereby killing many fragile microbes that cannot survive outside the range of body temperature, 35-40.5.degree. C. If the patient's blood is heated above about 40.5.degree. C., the blood begins to decompose, also becoming sterile, thus defeating the attempt to culture pathogens.
(e) Pathogens that grow in the lab do not always respond the same in the patient as general experience of the past indicates. As noted above, an ill patient has a unique mix of elements, most unknown to the physician. An antibiotic that may be effective in most people may not be effective in others and current art does not offer a way to determine this, except by using the patient. But, the patients who are most needy of immediately effective antibiotics are least able to withstand this process of experimentation.
(f) Even when successful, current art of pure culture, i.e., specific identification and isolation, requires much time to determine which antibiotic will be effective. For a few patients, a day saved may be a life saved. For many with chronic illnesses, such as AIDS, morbidity can be reduced by effective treatment of a secondary infection. For all, a day earlier institution of an effective antibiotic or medication is a day their illness does not worsen; hospitalization with its attendant costs and risks may be avoided. At the very least, patients can resume their active lives earlier, including going back to work. Delay in effective treatment is very expensive, both individually and nationally.
(g) Currently, many patients are tested after they are already taking antibiotics, medications, etc. This is considered to be a problem because the currently taken medications may suppress the pathogens and make them difficult or impossible to isolate in pure culture. With the process and devices described herein the patient's current natural state is desired, including any medications taken. Obtaining pure cultures is no longer an essential goal; however, traditional identification and sensitivity testing may still be done in two steps using the present invention.
(h) Currently, when tumors are removed from the body, they are usually adulterated in some way before they are examined or cultured, e.g., freezing, refrigerating, preservative solutions, etc. Consequently, tests of the tumor cells or the patient's cells or other factors are inaccurate or incomplete. The process and devices described herein use specimens in the natural state and under natural conditions, thus eliminating these limitations. For example, a bag-in-a-bag device can be used as a transport apparatus to convey tumors to the lab under natural conditions, using the patient's blood. Also the research process in the cancer lab may start in the bag with additives, such as collagenase, to separate cancer or other patient tissue cells. Such a device allows every cancer patient to have access to the expertise of a cancer research center even though that center may be remote.
(i) There is risk of life-threatening contamination to medical or lab staff who handle human blood, particularly when needles are used. Using current art, the results obtained from the process of this application would tend to only be the product of experts in laboratories, not of physicians in their offices where blood and specimens are fresh, unadulterated, whole, and at body temperature. Without the present invention, these results, so valuable in an era of increasingly resistant and virulent pathogens, would be unobtainable.
(j) Placing antibiotic discs on culture media one at a time by hand is time and labor consuming, while increasing the risk of contamination, so the physician almost always uses the lab for antibiotic sensitivity testing. Thus, current methods limit the physician to use of a lab, even though ideal conditions of blood and specimen are available in his/her office.